<style>
  .sk-double-bounce {
    width: 40px;
    height: 40px;
    position: relative;
  }
  .sk-double-bounce .sk-child {
    width: 100%;
    height: 100%;
    border-radius: 50%;
    background-color: #fff;
    opacity: 0.6;
    position: absolute;
    top: 0;
    left: 0;
    -webkit-animation: sk-doubleBounce 2s infinite ease-in-out;
    animation: sk-doubleBounce 2s infinite ease-in-out;
  }
  .sk-double-bounce .sk-double-bounce2 {
    -webkit-animation-delay: -1s;
    animation-delay: -1s;
  }

  @-webkit-keyframes sk-doubleBounce {
    0%,
    100% {
      -webkit-transform: scale(0);
      transform: scale(0);
    }
    50% {
      -webkit-transform: scale(1);
      transform: scale(1);
    }
  }

  @keyframes sk-doubleBounce {
    0%,
    100% {
      -webkit-transform: scale(0);
      transform: scale(0);
    }
    50% {
      -webkit-transform: scale(1);
      transform: scale(1);
    }
  }
</style>

<div class="sk-double-bounce">
  <div class="sk-child sk-double-bounce1" />
  <div class="sk-child sk-double-bounce2" />
</div>
